The rule is partly inspired by Spiegel's own parents not allowing him to watch TV until he was nearly a teenager. Instead, he told the FT he was encouraged to spend time "building stuff and reading or whatever."

Steyer, who lobbies for better protections for children online, said he was pleased to hear about Spiegel's approach with his stepson, but asked his billionaire former student: "How about limiting all the kids on Snapchat?"

He told Business Insider: "I'm glad to see Evan's worried about that [screen time] now, but Evan's been missing in action up until now. But he shouldn't be because teens are on his platform."

Steyer took particular issue with Snapstreaks, which encourage Snapchat users to keep on communicating by counting the consecutive days they have exchanged messages.

Jim Steyer, CEO of Common Sense Media. YouTube/Bloomberg

"Snapstreaks is a huge problem. That's like an intentionally addictive platform. Great that Evan's finally waking up. This is affecting every child's life, not just Evan's. And these guys [tech CEOs] are responsible," Steyer said, adding: "I haven't seen Evan show any social responsibility."

Snap declined to comment directly on Steyer's remarks. The company did say, however, that Snapchat is designed without public vanity measures such as "likes" and Snapstreaks are meant to be a playful way of deepening friendship.

Spiegel launched Snapchat while Studying at Stanford in 2011. Steyer said the tech CEO used to sit in his state of the union classes and "steal my daughter's notes."